Gr.9 (Alloy) Non-Serrated Frame Bolts: This bolt features a integrated flange with no serrations under the head and, depending on the diameter and length, a partially threaded shank. Available with a black phosphate finish, sizes range from 1/4" ~ 3/4" diameters. [A non-indented head is recommended as it prevents grease and dirt from accumulating on the head while providing a higher quality finish and appearance.]